The Experts below are selected from a list of 513 Experts worldwide ranked by ideXlab platform
Ken Izumori - One of the best experts on this subject based on the ideXlab platform.
-
l xylose and l Lyxose production from xylitol using alcaligenes 701b strain and immobilized l rhamnose isomerase enzyme
Enzyme and Microbial Technology, 2005Co-Authors: Tom Granstrom, Matti Leisola, Kenji Morimoto, Goro Takata, Ken IzumoriAbstract:Xylitol was used as a raw material for production of l-xylose and l-Lyxose using Alcaligenes 701B strain and immobilized l-rhamnose isomerase enzyme. Alcaligenes 701B converted xylitol to l-xylulose with a yield of 34% in the bioreactor. l-Xylulose was converted to l-xylose and l-Lyxose using immobilized l-rhamnose isomerase enzyme. The final equilibrium between l-xylulose, l-xylose and l-Lyxose was 53:26:21. The enzyme assays indicated that Alcaligenes 701B strain has an NAD-dependent xylitol dehydrogenase enzyme responsible for l-xylulose production. Furthermore, NAD(P)H-dependent l-xylulose reductase enzyme was active during conversion of xylitol to l-xylulose. The highest l-xylulose production rate corresponded with the highest growth rate. The Alcaligenes 701B strain used d-xylose for biomass growth, but xylitol was used only for l-xylulose production during conversion phase.
-
novel reactions of l rhamnose isomerase from pseudomonas stutzeri and its relation with d xylose isomerase via substrate specificity
Biochimica et Biophysica Acta, 2004Co-Authors: Khim Leang, Goro Takada, Yoshinori Fukai, Kenji Morimoto, Tom Granstrom, Ken IzumoriAbstract:Escherichia coli strain JM 109 harboring 6 x His-tag L-rhamnose isomerase (L-RhI) from Pseudomonas stutzeri allowed a 20-fold increase in the volumetric yield of soluble enzyme compared to the value for the intrinsic yield. Detailed studies on the substrate specificity of the purified His-tagged protein revealed that it catalyzed previously unknown common and rare aldo/ketotetrose, aldo/ketopentose, and aldo/ketohexose substrates in both D- and L-forms, for instance, erythrose, threose, xylose, Lyxose, ribose, glucose, mannose, galactose, altrose, tagatose, sorbose, psicose, and fructose. Using a high enzyme-substrate ratio in extended reactions, the enzyme-catalyzed interconversion reactions from which two different products from one substrate were formed: L-Lyxose, L-glucose, L-tagatose and D-allose were isomerized to L-xylulose and L-xylose, L-fructose and L-mannose, L-galactose and L-talose, and D-psicose and D-altrose, in that order. Kinetic studies, however, showed that L-rhamnose with Km and Vmax values of 11 mM and 240 U/mg, respectively, was the most preferred substrate, followed by L-mannose, L-Lyxose, D-ribose, and D-allose. Based on the observed catalytic mode of action, these new findings reflected a hitherto undetected interrelation between L-RhI and D-xylose isomerase (D-XI).
-
production of d Lyxose from d glucose by microbial and enzymatic reactions
Journal of Bioscience and Bioengineering, 1999Co-Authors: Zakaria Ahmed, Shakhawat Hossain Bhuiyan, Goro Takada, Hiroyuki Sasahara, Tetsuya Saiki, Tsuyoshi Shimonishi, Ken IzumoriAbstract:D-arabitol was first prepared from D-glucose using Candida famata R28. The reaction gave 5.0% D-arabitol from 10.0% D-glucose. D-arabitol was then almost completely converted to D-xylulose using Acetobacter aceti IFO 3281. Finally, D-Lyxose was prepared from D-xylulose enzymatically using L-ribose isomerase from toluene-treated cells of Acinetobacter sp. strain DL-28. The isomerization reaction progressed steadily and the concentration of D-xylulose increased from 1.0 to 10.0%. About 70% of D-xylulose was converted to D-Lyxose in all cases. Separation of residual D-xylulose from the reaction mixture is very difficult to achieve by column chromatography, but D-xylulose could be selectively degraded easily using Saccharomyces cerevisiae IFO 0841. The product was crystallized and was confirmed to be D-Lyxose by HPLC, 13C-NMR spectra, IR spectra analysis, and optical rotation measurement.
-
A new method for the production of l-Lyxose from ribitol using microbial and enzymatic reactions
Journal of Fermentation and Bioengineering, 1998Co-Authors: Shakhawat Hossain Bhuiyan, Zakaria Ahmed, Masaru Utamura, Ken IzumoriAbstract:Abstract l -Lyxose was prepared from ribitol by a new method comprising a potent microbial oxidation reaction to convert ribitol to l -ribulose, epimerization of the l -ribulose to l -xylulose, and isomerization of the l -xylulose to produce l -Lyxose. The complete transformation of ribitol to l -ribulose was achieved using washed cells of Acetobacter aceti IFO 3281 at high substrate concentrations ranging from 5–20%. The l -ribulose produced was then used as the substrate for the production of l -Lyxose using immobilized l -rhamnose isomerase ( l -RI) of Pseudomonas sp. strain LL172 and immobilized d -tagatose 3-epimerase ( d -TE) of recombinant Escherichia coli JM 105. At equilibrium, the yield of l -Lyxose from l -ribulose was determined to be about 60%, and the product could be isolated easily from the reaction mixture after degradation of ketoses using Pseudomonas sp. 172a. Following various product purification steps, about 5.0 g l -Lyxose crystals were recovered from 10.0 g ribitol in a flask reaction. The crystallized product was finally identified by HPLC, IR spectrum, NMR, and optical rotation measurements.
-
Isolation of an l-rhamnose isomerase-constitutive mutant of Pseudomonas sp. strain LL172: Purification and characterization of the enzyme
Journal of Fermentation and Bioengineering, 1997Co-Authors: Shakhawat Hossain Bhuiyan, Yoshiyuki Itami, Ken IzumoriAbstract:Abstract A soil bacterium, strain 172a, which inductively produced l -rhamnose isomerase ( l -rhamnose ketolisomerase, EC 5.3.1.14) and could not grow on l -Lyxose acquired the ability to grow on l -Lyxose following cultivation in a mineral salts medium containing l -Lyxose as the sole carbon source for about 4 d. This l -Lyxose-utilizing mutant (LL172) was isolated and found to produce l -rhamnose isomerase constitutively. Based on various bacteriological characteristics, the parent strain was identified as Pseudomonas sp. and the mutant was confirmed to be derived from the parent strain. l -Rhamnose isomerase was purified from extracts of Pseudomonas sp. LL172 by polyethylene glycol precipitation, anion exchange chromatography on DEAE-Toyopearl 650M and gel filtration on Sephadex G-150. The enzyme was found to be homogeneous by polyacrylamide gel electrophoresis. The apparent molecular weight of the enzyme was estimated to be 150,000 by gel filtration on Sephadex G-150. Based on sodium dodecyl sulfate (SDS) gel electrophoresis, the enzyme is most likely composed of 4 identical subunits of molecular weight of approximately 42,000. The enzyme was optimally active at pH 9.0 and was stable in the pH range of 5.0–11.0. The optimum temperature for activity was 60°C (10 min, pH 9.0) and the enzyme was stable up to 60°C (10 min, pH 9.0). The isoelectric point of the enzyme was estimated to be 5.1. The substrate specificity of the enzyme was broad and the enzyme required manganese ions for maximum activity. The K m for l -rhamnose isomerase was 55 mM and the V max was 182.6 U/mg. The equilibrium ratio between l -rhamnose and l -rhamnulose was 55:45.
J Colmenero - One of the best experts on this subject based on the ideXlab platform.
-
broadband dielectric spectroscopy and calorimetric investigations of d Lyxose
Carbohydrate Research, 2011Co-Authors: Lokendra P Singh, Angel Alegria, J ColmeneroAbstract:Abstract Using broadband dielectric spectroscopy, we have studied different types of relaxation processes, namely, primary (α), secondary (β), and another sub- T g process called γ-process, in the supercooled state of d -Lyxose, over a wide frequency ( 10 - 2 – 10 9 Hz ) and temperature range (120–340 K). In addition, the same sample was analyzed by differential scanning calorimeter. The temperature dependence of the relaxation times as well as the dielectric strength of different processes has been critically examined. It has been observed that the slower secondary relaxation (designated as β-) process shifts to lower frequencies with increasing applied pressure, but not the faster one. This pressure dependence indicates that the observed slower secondary relaxation (β-) is Johari–Goldstein relaxation process and faster one (γ-process) is probably the rotation of hydroxymethyl (–CH 2 OH) side group attached to the sugar ring, that is, of intramolecular origin.
Shunyuan Luo - One of the best experts on this subject based on the ideXlab platform.
-
concise synthesis of α galactosyl ceramide from d galactosyl iodide and d Lyxose
Carbohydrate Research, 2013Co-Authors: Yufen Yen, Suvarn S Kulkarni, Chunwei Chang, Shunyuan LuoAbstract:α-Galactosyl ceramide is synthesized from d-Lyxose in 32% overall yield in five steps. The short and efficient protocol involves a one-pot protection and glycosidation of d-Lyxose with d-galactosyl iodide as a key step. The α-linked disaccharide obtained was subsequently transformed into α-galactosyl ceramide in four steps involving Z-selective Wittig olefination at C-1, stereo-inversion at C-4 using azide, one-pot reduction of azide and amidation, and global deprotection.
-
Concise Syntheses of α-Galactosyl Ceramide, d-ribo-Phytosphingosine, and Ceramide
Synthesis, 2013Co-Authors: Shunyuan Luo, Yufen Yen, R. SawantAbstract:Total syntheses of α-galactosyl ceramide, d-ribo-phytosphingosine, and ceramide through an α-galactosyl phytosphingosine derivative as a common synthon were accomplished in overall yields of 26%, 15%, and 20% in nine, seven, and eight steps, respectively, starting from an acetonide-protected d-Lyxose derivative. This short and efficient protocol involved protection and glycosylation of the acetonide-protected d-Lyxose with d-galactosyl iodide as a key step. The resulting α-linked disaccharide was subsequently transformed into α-galactosyl ceramide, phytosphingosine, and ceramide
Yufen Yen - One of the best experts on this subject based on the ideXlab platform.
-
concise synthesis of α galactosyl ceramide from d galactosyl iodide and d Lyxose
Carbohydrate Research, 2013Co-Authors: Yufen Yen, Suvarn S Kulkarni, Chunwei Chang, Shunyuan LuoAbstract:α-Galactosyl ceramide is synthesized from d-Lyxose in 32% overall yield in five steps. The short and efficient protocol involves a one-pot protection and glycosidation of d-Lyxose with d-galactosyl iodide as a key step. The α-linked disaccharide obtained was subsequently transformed into α-galactosyl ceramide in four steps involving Z-selective Wittig olefination at C-1, stereo-inversion at C-4 using azide, one-pot reduction of azide and amidation, and global deprotection.
-
Concise Syntheses of α-Galactosyl Ceramide, d-ribo-Phytosphingosine, and Ceramide
Synthesis, 2013Co-Authors: Shunyuan Luo, Yufen Yen, R. SawantAbstract:Total syntheses of α-galactosyl ceramide, d-ribo-phytosphingosine, and ceramide through an α-galactosyl phytosphingosine derivative as a common synthon were accomplished in overall yields of 26%, 15%, and 20% in nine, seven, and eight steps, respectively, starting from an acetonide-protected d-Lyxose derivative. This short and efficient protocol involved protection and glycosylation of the acetonide-protected d-Lyxose with d-galactosyl iodide as a key step. The resulting α-linked disaccharide was subsequently transformed into α-galactosyl ceramide, phytosphingosine, and ceramide
Wenli Zhang - One of the best experts on this subject based on the ideXlab platform.
-
identification of a novel recombinant d Lyxose isomerase from thermoprotei archaeon with high thermostable weak acid and nickel ion dependent properties
International Journal of Biological Macromolecules, 2020Co-Authors: Ming Chen, Cuie Guang, Wenli ZhangAbstract:Abstract Recently, production of D-mannose becomes a hotspot owing to it exhibiting many physiological functions on people's health and wide applications in food and pharmaceutical field. The use of biological enzymes to production of D-mannose is of particular receiving considerable concerns due to it possessing many merits over chemical synthesis and plant extraction strategies. D-Lyxose isomerase (D-LIase) plays a pivotal role in preparation of D-mannose from d -fructose through isomerization reaction. Thus, a novel putative D-LIase from thermophiles strain Thermoprotei archaeon which was expressed in E. coli BL21(DE3) was first identified and biochemically characterized. The recombinant D-LIase showed an optimal temperature of 80 and 85 °C and pH of 6.5. It was highly thermostable at 70 °C and 80 °C after incubating for 48 h and 33 h, respectively, with retaining over 50% of the initial activity. A lower concentration of Ni2+ (0.5 mM) could greatly increase the activity by 25-fold, which was rare reported in other D-LIases. It was a dimer structure with melting temperature of 88.3 °C. Under the optimal conditions, 15.8 g L−1 of D-mannose and 33.8 g L−1 of D-xylulose were produced from 80 g L−1 of d -fructose and D-Lyxose, respectively. This work provided a promising candidate sugar isomerase T. archaeon D-LIase for the production of D-mannose and D-xylulose.
-
characterization of a novel d Lyxose isomerase from thermoflavimicrobium dichotomicum and its application for d mannose production
Process Biochemistry, 2019Co-Authors: Wenli Zhang, Jiawei Huang, Min Jia, Cuie Guang, Tao ZhangAbstract:Abstract d -Mannose is the aldose isomer of d -fructose and displays unique physiological functions and health applications. As a result, it has attracted increasing interest from the public. Because of its wide substrate specificity, d -Lyxose isomerase (D-LI) has been applied to d -mannose bioproduction. In this article, the Thermoflavimicrobium dichotomicum D-LI encoding gene was cloned and overexpressed in Escherichia coli BL21(DE3). The novel protein T. dichotomicum D-LI was identified and characterized, and its maximum enzyme activity was exhibited at pH 7.5 (phosphate buffer) and 60 °C in the presence of Mn2+. Similar to other D-LIs, T. dichotomicum D-LI formed a homodimeric structure and showed strict conservation of the metal coordination and substrate binding sites. The D-LI half-life (t1/2) was 9.91 h and 3.05 h at 55 and 60 °C, respectively, and its melting temperature (Tm) was 72.85 °C. T. dichotomicum D-LI displayed the highest specific activity towards d -Lyxose among the substrates tested, followed by d -mannose. It also efficiently converted d -fructose to d -mannose, and the equilibrium ratio between d -mannose and d -fructose during T. dichotomicum D-LI activity was 25:75. From 500 g/L d -fructose, 110.5 g/L d -mannose was produced after 6 h, suggesting that T. dichotomicum D-LI might provide an alternative for d -mannose production.
-
d Lyxose isomerase and its application for functional sugar production
Applied Microbiology and Biotechnology, 2018Co-Authors: Jiawei Huang, Ziwei Chen, Wenli Zhang, Tao ZhangAbstract:Functional sugars have attracted attention because of their wide application prospects in the food, cosmetics, and pharmaceutical industries in recent decades. Compared with complex chemical synthesis, enzymatic methods of creating functional sugars, characterized by high specificity, moderate reaction conditions, and sustainability, are favored. D-Lyxose isomerase (D-LI, EC 5.3.1.15), an important aldose-ketose isomerase, catalyzes the reverse isomerization reaction between D-xylulose and D-Lyxose, as well as D-fructose and D-mannose. D-LI has drawn researchers' attention due to its broad substrate specificity and high potential for enzymatic production of some functional sugars such as D-xylulose, D-mannose, and D-ribose. In this article, an overview of recent advances in the biochemical properties of various D-LIs is explored in detail. Structural analysis, active site identification, and catalytic mechanisms are also provided. Additionally, the applications of D-LIs for functional sugar production, including D-Lyxose, D-mannose, and L-ribose, are reviewed in detail in this paper.
-
efficient biotransformation of d fructose to d mannose by a thermostable d Lyxose isomerase from thermosediminibacter oceani
Process Biochemistry, 2016Co-Authors: Wenli Zhang, Tao Zhang, Bo JiangAbstract:Abstract d -Mannose has prebiotic effect and potential medical application. Besides, it can be used as substrate to produce mannitol, a functional polyol widely used in food industry. As this result, it has attracted many researchers’ attention. In this work, a thermostable d -mannose-producing d -Lyxose isomerase (D-LI) was characterized from a hyperthermophile, Thermosediminibacter oceani . The recombinant D-LI could be remarkably activated by Mn 2+ . It displayed maximal activity in presence of 1 mM Mn 2+ at pH 6.5 and 65 °C, and was determined to be highly thermostable at 80 °C. The half-life was calculated to be 5.64, 2.82, 0.77, and 0.2 h at 70, 75, 80, and 85 °C, respectively. The enzyme showed the optimum activity using d -Lyxose as substrate and could also effectively catalyze the isomerization between d -fructose and d -mannose. Under optimum conditions, 101.6 g/L d -mannose was produced from 400 g/L d -fructose after reaction for 9 h, giving a conversion yield of 25.4%.
